View full size(Press-Register/Bill Starling)An apparent victim of an ammonia release is taken on a stretcher to a waiting ambulance Monday Aug. 23, 2010. The leak at the refrigeration plant on the Theodore Industrial Canal started from a failure in the piping system, an official with the U.S. Occupational Health and Safety Administration said today.

MOBILE, Ala. -- The Monday ammonia leak at a refrigeration plant on the Theodore Industrial Canal was the result of a failure in the piping system, an official with the U.S. Occupational Safety & Health Administration said Tuesday.

Ten people injured in the leak were still hospitalized as of late Tuesday afternoon, including two in intensive care, a day after more than 100 people flooded emergency rooms. At least 10 more people went to emergency rooms with respiratory problems on Tuesday.

Kurt Petermeyer, OSHA area director in Mobile, said that investigators were probing the cause of the leak at Millard Refrigerated Services, including exactly how much of the harmful gas was released into the air and who was injured.

A white plume billowed from the refrigeration plant on Deer River Road on Monday morning, forcing residents within a one-mile radius to take shelter and causing breathing problems for people exposed to the gas.

Millard, based in Omaha, Neb., prepares chicken parts for export around he world. Ammonia is used in the refrigeration process.

Petermeyer said the company stores 148,000 pounds of ammonia at the Theodore facility. So far, he said, there were no reports of any Millard employees being injured in the leak, although people at nearby businesses were affected.

He said it was “gravely concerning” that some patients were still being treated in intensive care units.

In a statement Tuesday, the company said it was working with authorities to determine the exact cause of the leak, which was detected on the roof of the building about 9:05 a.m.

"First, we would like to extend our sincerest apologies to those who reported medical issues or who may have experienced discomfort as a result of the leak," said Lance Larsen, Millard chief executive officer and board chairman. "We followed our protocol to alert the authorities and evacuate our facility."

At the time, there were 74 employees at the plant, company officials said. One employee, a crane operator, was taken to the hospital and released a short time later.

Four of the plant’s five freezers have been deemed safe for use by the U.S. Department of Agriculture, the company said, and the facility is expected to be fully operational today.

Millard paid a $5,100 penalty following a 2007 OSHA inspection of its Theodore site, according to agency records. Violations centered on control of hazardous chemicals, failure to secure machinery and record-keeping. OSHA inspected the facility in 2005 and 2006 and found no violations.

An estimated 400 to 800 gallons of ammonia were released in the Monday incident, according to Capt. Shaun Hicks with the Mobile Fire-Rescue Department.

Alarm sirens warned people to take shelter and turn on televisions or radios for more information, officials said. Residents were asked to stay indoors and turn off air conditioning units.

Ronnie Adair, director of the Mobile County Emergency Management Agency, said his agency was notified about the leak at 9:35 a.m. and sounded alarms by 9:50 or 9:55 a.m.

Last year, Mobile County and the county EMA dropped out of a system that uses automated calls to warn residents of chemical spills or hazardous weather. At present, the calling system covers only residents in the city of Mobile and Mobile’s police jurisdiction.

Officials said grants and state money that covered the county’s and EMA’s participation dried up. The city of Mobile continues to pay for the service.

On Tuesday, Adair said that having the call system during the ammonia leak could have helped alert residents who didn’t hear the sirens or weren’t watching TV.

“None of these things are 100 percent guaranteed,” Adair said. “It’s just the more tools you have in your toolbox, the better chance you have of getting somebody notified.”

Mobile County Commissioner Mike Dean, in a Tuesday statement, said the commission is considering rejoining the alert system but “will have to weigh whether we have the funds in light of lower revenues and other priorities of the county.”

“The county believes that the response to the chemical spill was well managed by the EMA and the local fire department teams,” Dean said.

At Infirmary West, the closest hospital to the leak, 60 people were treated, including 10 who arrived Tuesday complaining of problems.

“We filled up every room,” said Eric Hartigan, manager of critical care and emergency services at Infirmary West. “We were treating patients in every area we could treat them in” from 10 a.m. until 5:30 p.m. Monday.

Hartigan said four patients remaining Tuesday evening were in fair condition.

“They are going to do fine,” Hartigan said. “Physicians want to make sure they are doing well, respiratory wise.”

Hospitals typically run drills every few months to prepare for emergency situations, Hartigan said, noting that emergency department staff at Infirmary West did such a run-through several months back with a situation similar to what happened Monday.

At Mobile Infirmary Medical Center, a total of 18 patients were seen in the emergency department Monday, with two others treated there Tuesday, said spokeswoman Lauren Giddens. All the patients at Mobile Infirmary were treated and released, she said.

At the University of South Alabama Medical Center in Mobile, at least 20 patients were admitted to the hospital Monday, with 16 patients under observation and four others in intensive care, according to spokesman Bob Lowry. By Tuesday evening, only one patient was in ICU there, with five other patients still under observation.

Springhill Medical Center in Mobile saw a total of 25 patients Monday, though all were treated and released, a spokeswoman said.

Providence Hospital treated a total of 23 people after the ammonia leak Monday, with six of those remaining hospitalized over night. All but one of the patients had been sent home by 2 p.m. Tuesday, a hospital official said.

(Staff Reporter Casandra Andrews contributed to this report. Updated at 7:22 p.m. and at 9:28 p.m. with Millard statement.)